This is a double-blind, placebo-controlled, randomized, cross-over study to determine the central and peripheral effects of two commonly used anticholinergic agents (biperiden and trihexyphenidyl) in 15 normal volunteers. Anticholinergic agents are often used to treat acute onset neuroleptic-induced movement disorders in schizophrenic patients. An anticholinergic agent that exhibits a higher ratio of central to peripheral anticholingeric effects would be advantageous in this group of patients.